Polyester polyamide blend fiber dyed with azo disperse dye

ABSTRACT

Fibers are prepared which are comprised of 4-50 parts by weight of a substantially linear fiber-forming polyester having recurring cyclic structure in the polymer backbone dispersed in a continuous body of 50-96 parts by weight of a linear fiberforming polyamide, said fiber having at least 5,000 polyester microfibrils per 1,000 square microns cross section and is dyed with an azo disperse dye having a solubility of less than 0.1 gram is 100 cc. of water and which has an apparent electron affinity of greater than 3 electron volts, said azo disperse dye having one or more electron attracting substituent moieties, and there may be simultaneously present electron repelling substituent moieties, provided the sum of the charges of the electron attracting moieties are at least 0.5 electron volts greater than the sum of the electron repelling moieties. The fibers may be blended with other fibers to form fabrics having novel effects. A process for producing said dyed polyblend fibers or fabric therefrom comprising dyeing in an aqueous medium at a temperature of at least 150* F. as the sole fiber in the textile article or in combination with at least one other fiber selected from the group consisting of polyamide, polyester, polyacrylonitrile, polypropylene, cotton, silk and wool, said dye being solely an azo disperse dye having an electron affinity of at least 3.0 electron volts and alternately there may be simultaneously present, for multicolor effects, one or more dyes selected from the group, acid dyes, acid metallized dyes, direct dyes, basic dyes, and anthraquinone disperse dyes.

States Patent Snider et al. 51 Jan. ll, W72

[54] POLYESTER POLYAMIDE BLEND FIBER DYED WITH AZO DISPERSE ABSTRACT DYEFibers are prepared which are comprised of 4-50 parts by [72] Inventors:Orville Snider, Petersburg Vax James weight ofa substantially linearfiber-forming polyester having E Loughlin Charlotte C Hans recurringcyclic structure in the polymer backbone dispersed o'mlen S artanbur S Cin a continuous body of 50-96 parts by weight ofa linear fiberp formingpolyamide, said fiber having at least 5,000 polyester [73] Assignee:Allied Chemical Corporation, New York, microfibrils per 1,000 squaremicrons cross section and is N.Y. dyed with an azo disperse dye having asolubility of less than 0.1 gram is 100 cc. of water and which has anapparent elec- [22] 1967 tron affinity of greater than 3 electron volts,said azo disperse [2l] Appl. No; 682,572 dye having one or more electronattracting substituent moieties, and there may be simultaneously presentelectron repelling substituent moieties, provided the sum of the charges[52] U.S.Cl ..8/21,28/75,260/857, of the electron attracting moietiesare at least 05 electron 8/178 8/179 volts greater than the sum of theelectron repelling moieties. [5]] Illll. Cl. ..D06p The fibers y beblended with other fibers to form fabrics 58 Field of Search ..s/17s,lzvg/zslgislgf/gs having novel effects A process for producing said dyedpolyblend fibers or fabric [56] Refe en e Cited therefrom comprisingdyeing in an aqueous medium at a temperature of at least 150 F. as thesole fiber in the textile article UNITED TATE PA ENT or in combinationwith at least one other fiber selected from 3 493 316 2/1970 Orthefl8/21 X the group consisting of polyamide, polyester, polyacrylonitrile,polypropylene, cotton, silk and wool, said FORElGN PATENTS ORAPPUCATIQNS dye being solely an azo disperse dye having an electronaffinity 999 878 7/1965 6 B 8/21 of at least 3.0 electron volts andalternately there may be reat ritam Primary ExaminerGeorge F. LesmesAssistant Examiner-Patricia C. lves A!t0rneyFrancis W. Guay and Roy H.Massengill simultaneously present, for multicolor effects, one or moredyes selected from the group, acid dyes, acid metallized dyes, directdyes, basic dyes, and anthraquinone disperse dyes.

8 Claims, N0 Drawings POLYESTER POLYAMIDE BLEND FIBER DYEI) WITH AZODISPERSE DYE BACKGROUND OF THE INVENTION It is known that polyamides,particularly nylons such as nylon 6, and nylon 6,6 can be effectivelydyed employing a wide range of dyestuffs. It is also known thatpolyesters can be dyed satisfactorily only with a limited range ofdyestuffs, and in general with dyeing procedures substantially moreelaborate than those employed with nylon. Thus, it would be expectedthat nylon/polyester melt blends would dye in relationship to theirpercentage composition someplace in between the strong dyeing of nylonand the weak dyeing of polyesters.

Unexpectedly it has been found that fibers made from dispersions ofpolyesters in polyamides, hereinafter referred to as PE-PA blends,absorb many acid dyes, dispersed dyes, and direct dyes at materiallylower rates and concentrations than could have been postulated from theknown concentrations of the dyestuffs present and the polyester contentof the blend fiber employed.

Heretofore, it would have been predicted that the quality of dyeingachievable with such blends would depend upon the relative proportionsof each ingredient in the blend, and that the quality would be poorerthan that obtained with pure nylon. While these expectations have beensubstantiated with most dye classes, it has now been found that fibersprepared from such blends exhibit highly unusual dyeing characteristicswith a certain class of dyes. More specifically, it has been found thatthese blends display a remarkable afirnity for monoazo disperse dyeshaving a higher apparent electron affinity, that is, having substituentson the aromatic rings which have a high dipole moment and which arestrongly electron attracting.

It has long been a problem in the dyeing of nylons to obtaintone-on-tone effects with sufiiciently great contrast between the nylonsto produce the desired design effects. One problem with nylon is thatinsufficient depths of dye shade, light fastness, and wash fastness areobtained with those dyes that give adequate leveling or uniform dyeing.It is still another problem with nylon that when nylons are dyed inmulticolor with other fibers in a fabric in single or in multiple dyebaths to produce a multicolored fabric in one operation, or successiveoperations, clear, bright multicolor effects normally are not obtainedbecause of the strong afiinity and similarity of nylon and their dyeingcharacteristics with most of the dye systems employed, making it quitedifi'lcult to obtain clear bright shades as are desired in most end-useapplications of the multicolored fabric. Frequently such multicolordyeings of fabrics show an undesirable muddiness of color.

SUMMARY OF THE INVENTION In accordance with the present inventionpolyester/polyamide blend fibers are dyed with a dye selected from agroup of disperse organic dyes which have a solubility in water of lessthan 0.1 gram per 100 cc. of water and said dyes being electronattracting and having an apparent electron affinity which is greaterthan 3.0 electron volts, said dyes being principally disperse azo type,said fiber comprising of substantially uniform dispersion of 4 to 50parts by weight of polyester in a continuous body of 50 to 96 parts byweight of polyamide per 100 parts by weight of total polyamide andpolyester wherein the polyester is comprised of a substantially linearfiber-fonning polyester having recurring cyclic structure in the polymerbackbone and having a reduced viscosity of about 0.3 to 1.1 decilitersper gram and the polyamide is comprised of a substantial linearfiber-forming polyamide having a reduced viscosity of about 0.6 to 1.3deciliters per gram. The polyester is dispersed in the said polyamide inthe form of discrete microfibers which occur at an average of at least5,000 polyester microfibrils per 1,000 square microns in a drawnfilament cross section.

It has been discovered that the PE-lPA blends useful in this inventionmanifest several unusual properties in conjunction with high electronaffinity azo disperse dyes; these are:

l. The dyeing characteristics can be modified with change 5 in thenumber of polyester fibrils in a given filamentary cross section. 2. Theimproved dyeing characteristics are relatively insensitive to changes inpH. 3. The dyeing characteristics vary with varying polyester content.4. The improved dyeing characteristics are obtained at temperaturesbelow 100 C. and at atmospheric pressures. The remarkable high affinityof electron attracting azo l 5 disperse dyes for PE-PA fiber blends isunexpected when the relatively poor affinity of these dyes forpolyesters is considered at temperatures below 100 C. In view of theprior art it would not have been predicted, that by incorporation ofpolyesters in the polyamides, there would result in a product havinggreater affinity for these classes of dyes with increasing polyestercontent. Thus, it is quite remarkable that it has now been foundpossible to produce novel dye products from polyamide/polyester blendswith even better color characteristics than can be produced by dyeingthe same products produced from the parent polyamide or polyester. Thisfact coupled with the unusual dyeing characteristics of the blend attemperatures below 100 C. and with respect to changes in plil andpolyester content and with the number of polyester fibrils for a givencross section now makes it possible for the production of productsexhibiting interesting useful and unusual dyeing effects which have notheretofore been possible.

The process of this invention is applicable to composite filamentarystructures including yarns, cords, fibers and fabrics where at least onecomponent of which is a filament obtained by melt spinningpolyester/polyamide blend. It is applicable to fabrics frommonofilaments, multifilaments, yam, staple, continuous filament, andvarious crimpedl, bulked and textured yarn products made therefrom. Inthe simplest case, the struc- 40 tures to be dyed will be comprised offibers derived from a polyester/polyamide blend containing a singleproportion of polyester. In alternate cases there will be present fiberswith varying proportions of polyester; and there will be present otherfibers which will include nylon 6, nylon 6,6, nylon 7, nylon 8, nylon11, nylon 12, and polyamide made by reaction of bis (para aminocyclohexyl) methane and aliphatic dibasic acids of C6-Cl6. The PE-PAblend fibers with or without another polyamide may be dyed incombination with one or more other fibers including natural andsynthetic fibers such 50 as polyesters, specifically polyethyleneterephthalate, polyacrylonitrile, polyacrylics containing at least 80percent polyacrylonitrile, cellulose acetate, cellulose triacetate,rayon viscose, and polyolefin fibers. Other natural fibers may be usedin staple blend combinations or as individual fibers such as cotton,wool, and silk.

These fibers may be formed into fabrics by weaving,

knitting, felting, carding, braiding, plaiting, spin-bonding, tufting,needling, etc. 60 The preferred polyester/polyamide blends useful inthis invention comprise dispersions of poly-ester and polyamidescontaining from about 4 to about 50 parts by weight of polyester in acontinuous body of 50 to 96 parts by weight of polyamide per 100 partsby weight total polyester and polyamide. The polyesters in which theblends are prepared are sub stantially linear fiber-forming polyestershaving recurring cyclic structures in the polymer backbone with reducedviscosity as measured at 25 C. in orthochlorphenol at a polymerconcentration of 0.3 grams per 100 grams of orthochlorphenol of fromabout 0.3 to 11.1 deciliters per gram. This viscosity hereinafter isreferred to as OCPR viscosity.

The polyamides employed in the blends useful in this invention aresubstantially linear fiber-forming polyamides having an OCPR viscosityof from about 0.6 to 1.3 deciliters per gram.

lOl0l9 0332 The blends are preferably prepared by melt blending suitablepolyester polyamides in an extruder at a temperature of about 260 toabout 285 C. at a shear rate of at least I reciprocal seconds andextruding through a spinneret at an apparent sheer within the spinneretfrom about 2,000 to 32,000 reciprocal seconds. The terminal groups inthe polymer, especially amine terminal groups in the polyamide may ormay not be blocked, for example with monoor dibasic-acids.

The preferred polyesters are polyethylene terephthalate although othersmay be employed, more specifically those in which the recurring unit inthe polyester chain is the diacyl aromatic radical from terephthalicacid, isophthalic acid, 5-T- butylisophthalate, or naphthalenedicarboxylic acids such as naphthalene-2,6 andnaphthalene-2,7-dicarboxylic acids.

The preferred polyamides are polycaproamide or polyhexamethyleneadiparnide since these are most readily available commercially. Otherswhich are prepared from polyamide forming monomers containing four to 14carbon atoms can also be used, specifically nylon 7 (polyenanthoamide),nylon 8 (polycapryloamide), nylon ll (polyundecylamide) and nylon l2(polylaurylamide).

The nylon 7 exhibits dyeing characteristics very similar to nylon 6 andthe nylon 8 exhibits dyeing characteristics very similar to nylon 6 andnylon 6,6. However, using nylon l l and nylon l2, more stringent dyeingconditions are necessary and these exhibit comparatively low dyeabsorption and may be utilized, as an example, for higher degree ofcontrast between nylon 6 and 6,6 and as a degree of contrast between thepolyblends.

Suitable blends are described more fully in U.S. Pat. application, Ser.No. 368,028 filed May 18, 1964, now U.S. Pat. No. 3,369,057 issued Feb.13, 1968, assigned to the same assignee as this application.

The individual drawn filaments will typically have a thickness in theorder of about 1 to 25 denier per filament and will have thecharacteristic structure comprising microfibers of the polyesterdispersed in a substantially continuous body of polyamide. The size,configuration and distribution of the polyester microfibers will vary,depending upon the chemical and physical nature of the polyester andpolyamide, the relative proportions of each, the blending and spinningconditions employed, the draw ratio, and any additional treatment of thefibers. In preferred embodiments of this invention the polyestermicrofibers will have an elongated configuration with the longest axisof the microfiber substantially parallel to the fiber axis. The averagediameter of the microfibers in the drawn filamentary structure will bewithin the range of about 0.1 microns up to about 0.4 microns andpreferably about 0.01 to 0.3 microns. The average microfiber length maybe in the order of about 50 to 800 microns. The length to diameter ratiois desirable between about 150 and 40,000. The number of microfiber-sper l,000 square microns of drawn filamentary cross section willtypically be about 3,000 to 130,000 and preferably well above 5,000polyester microfibers.

In accordance with certain of its aspects, the process of this inventionfor producing dyed fibers comprises dyeing a PE-PA melt blend fiber withan organic insoluble dye (solubility less than 0.1 gram per 100 cc. ofwater), the azo dye having an apparent electron affinity of greater than3.0 electron volts, and said azo dyes employed have substituted thereonat least one or more groups of the electron attracting substituentsconsisting of nitro (RNO an aldehyde (RCHO), an ester RCOOC H andhalogens such as chlorine, bromine, fluorine and iodine (RC1, RBr, Rl,RF) and aliphatic substituents R-R and N or N,N' substituted nitrogenmoiety where R is one or more aromatic rings, R is an aliphaticsubstituent moiety and R, and R are independently selected from thesubstituent moieties H, and (CH and n is an integer of l-S and A,B areterminal moieties selected from the group hydrogen (H), ketone (COCHnitrile (C' N) and hydroxyl(OH), and R, and R are independently selectedfrom the substituent moieties (H), (CH,),,,, where n is an integer ofl-5 and Y and Z are independently selected from the terminal moieties,hydrogen (H), nitrile(CEN), ketone (CO-CH and hydroxyl (OH) provided onemoiety, a nitrile CEN, or ketone (COCH is always present. There may besimultaneously present on the ring, along or in conjunction with otherelectron repelling groups such as dialkyl and aryl amines RN(CH RaD R-Nwhere R, and R are independently selected from the substituent moietiesH, (CH and n is an integer of l5 and D and E are terminal substituentsindependently selected from the moieties hydrogen H, and OH; where R isone or more aromatic rings.

The above description of the substituent moieties requires that the sumof the electron attracting group is at least 0.5 electron volts greaterthan the sum of the electron repelling groups.

The electron repelling groups tend to decrease the affinity of the azodye for PE-PA blend fibers. However, when an electron repelling groupand a strong electron attracting group are simultaneously present, thereresults an increase in the electron affinity of the electron attractinggroup, in a general manner to the change in the polar charges or dipolemoment.

We have found that the maximum dye absorption occurs where there issimultaneously present on separate rings of a mono azo dye at least oneor more aromatic substituent nitro groups, at least one aromatic oraliphatic C N substituent group and alternately an aromatic substituentmoiety, a halogen, typically chlorine.

The description of the influence of electron attracting substituents andthe electron releasing substituents on dipole moment is described onpage 627 Advanced Organic Chemistry by Feiser and Feiser, ReinholdPublishing Company, l96l.

It is known that dipole moments are a complex vector function of thecharge and their distance in complex molecules such as azo dyes wheremultiple substitution of the aromatic ring occurs. However, we have nowfound that there is such a marked difference in dipole moments betweenthe disperse dyes which have a strong afiinity for the PE-PA blendfibers of this invention and the dipole moments of the azo disperse dyeswhich do not have a strong affinity for PE-PA melt blend fibers that anempirical electron affinity may be calculated which we hereinafterdesignated as an apparent electron affinity. This apparent electronaffinity is calculated by adding dipole moments of the electronattracting substituents on the same ring and subtracting the dipolemoments for the electron releasing substituents as given by Feiser andFeiser in the above-cited reference, and by Smyth Dielectric Behaviorand Structure," McGraw & Hill, 1955, pages 260-3ll and especially page 3l4, and pages 3 l5-354.

ye affinity for invention for ye strength and light bers of this re duein large part to the s used and the unexpected fibers to donate or sharegive reduced dye affinity with PE-PA melt blend fibers employed in thisinvention as compared to the d nylon. It is postulated that theexcellent d fastness properties of the PE-PA fi azo dyes as comparedwith nylon a electron attracting forces of the dye tendency of the PE-PAmelt blend electrons.

in only electron repelling substituents The numerical dipole moments(for calculation of apparent electron affinity) for common substituentsfound on azo dyes are given in table 1.

The best correlation with dye strength is obtained where the 5 apparentelectron affinity charges of two aromatic rings of the disperse azo dyemolecules are totaled. All disperse azo dyes investigated which conta I.I S I 1 I t. 2 .I I I Z t 2 S 3. we 3 I .2 2: n .Q .a I .I 2 *I I .3 3in I 2 Rd .3 on ow I 2.21.; aux co u m L N LA 2 2 Zn So an QN m .3 c v eN m M3 02 A T 55. La La 5 .3 La 2 2 g 2 I t: I I 8 t: E *2 .2 .I. Z T 2z. .I :1 .I LI I R I 1N 3 t.. 33 L .3 3 RM re 2 Le Q T 2.5 C a F 3 .3 We3 me o I 2 ea 3 Z .3 MS 2 Z 3 we 3 T 5. I.. we 3 a .e we Qe .e I .2 Wm.2 ea 5 Z 2 2 Z ow z T L202 Eu 2/ on we 3 em I we fie g Qm I 2 e QM E mNe ea 2 2 2 T 255 z m o 3: 2 tow a.. a; E L.. .2 Ne Se sea ed :2 med 2mom i N 2 ed .2 m o 9. E5. L3 33 E .3 1. I I .3 L; .2 to la 2 an *3 :2t: 12 I a: T E0 2 2 0: IN La 3 0e .ee .2 *3 re 2 .2 .6 id 1 1 tea I g T.:0 02 M56321 :o uu I s w m w I I I :I an 5 NM 2 I IN 2 mm 5 3 ca 2 5. II I I I I I I 2% we 2 .2 2 3 MN 2 I a I 262 5025/ m e h w v I a I iI I Im .2 2 Mn :3 2 ea 2 I 25 0 203.72 t. I I NI 1. 3 I I e Z *I 3N 2m Q3 2Ed 3% Ni 3+ e? s. 500 I I ..I .I *I I *I 3 v N I I I 3 WM 3 I I. I 3 20200 .5. I I t I I i.. S t. N I N I I I 3 I I m I I 25 0 00 .I L. QI I I*I *I 8 2e m 8w 3 mom 2 32 m *2 I we 53 x. 3 6.2 :1 v. I i I to. 3 *I2.. E 2 2 ed 2 2 ea I I .w an R62 2:82 I a 3 1 I .I *I *I i.. 3 f I I .32 I am I we g 25 0 3.0.2 I a a. I I I I 3 3m *3 i2 EA 93 5m .3 2a .3 5e3 3 S. .z I I ...I 3 I I SI 3 2.. *2 the LE in *2 *2 3 La 3 g 22 2 I mS .m I I 3 3 2m 3 *3 *I *I t. N F. 2 Qm 1% v3 2.5 22 I 3 e 3 i @I 3 a. 3.5. i3 NI .I OI Em 2 1a mom I 21 n. Eu I .I 2 ..I .I t: .I I 3. *I *3 m.wI WI L. w: :2 3H 2 3 $2250 I .I 5 I .I L 2 i .I .I t: 2 .I 3 2 .I 3o *2*2 m 2 u u z $100 $6 fie 250 :0 :2 1 20.2 :o ui z m 0;. u. m focco 6$500 9 6 z u oz 25:62 2 5. I Euicmss I e. .2. e. 9 .I NI .3. we. 8 02 19 MI .I 3 3m in m S2 2 .2 3. 25: 2 2.55 b 5:62 @085 3.3.55 1 1 1:52.51sebum-m .3m 3350 emu-: m::um..: co uom mcz zo .5. mu:

FOOTNOTES FOR TABLE 1 NHz i =1.49 electron repelling.

RiCEN N\ =4.68 electron attracting.

Ri C H *2 Estimated approximate values, electron repelling.

R|-CEN N =5.0 approximate value electron attracting.

RiCEN (CIIQ),.CN

N\ =5.08 approximate value, electron attracting.

"=Approximate values, all others measured values in benzene.

R =Alipliatic substltucnts of (Ciig) where n is an integer of 1--5.

\ =.97 repelling, approximate value.

R O II RrO H N\ =1.8 repelling, approximate value.

NR1OH 1.0 repelling, approximate value.

*3 These values are electron attracting under the electron repellingcolumn. All other values are electron repelling or attracting asspecified under their column designation unless otherwise indicated. Thedipole moments are a complex vector function expressed in Dobye units.Such a value is a practical method of expressing the affinity orattraction forces between a dye and the polyblend fibers of this instantinvention-- 5. Glasstone Textbook of Physical Chemistry, 2nd editionReprint 1954 von Nostrand Company, Inc., on page 41l has defined theelectron affinity of halogens, Br, Cl, and I in kilo calories andfurther states that this is more commonly expressed as electron voltswith conversion between kilo calories and electron volts given as 23.05kilo calories equals 1 electron volt. In conversion of the geometricvector Dcbye dipole moments to electron volts, the same values areapproximately 2.4 to 2.7 times the dipole moment. For purposes ofsimplification we have retained the dipole moments as the basicnumerical values, and have designated these values as parent electronafiinity in electron volts. A more accurate value for an electron voltvalue may be calculated in the dyeing of polyblends typically disperseazo dyes which have special affinity for the PE-PA blend fibers arethose which contain at least two substituent groups, simultaneouslypresent on one or more aromatic rings, selected from the groups ofsubstituents consisting of RCEN, R(CH ),,C= N,

RNO a R-X and R--CH ),,X, where R is an aromatic ring, X is a halogen,c.g., chlorine, bromine, iodine or fluorine and n is an integer of from1-5. To illustrate the difference in nylon dyeings and the polyblends ofthis invention with azo disperse dyes, the polyblend fiber properties asillustrated in table 3 and may be compared with a nylon 6 control fiber.The nylon 6 control fiber had 49 carboxyl end groups per kilogram ofpolymer and 48 amine groups per kilogram of polymer. A 30 percentpolyester 70 percent polyamide blend fiber whose properties are alsodesignated in table 3 was dyed competitively in the same bath. Bothfibers were scoured with 0.2 percent Naccanol SL and 0.2 percent sodaash for 10 minutes at 85 C., prior to dyeing. The 0.2 percent refers topercent scouring agent by weight of fabric.

The materials were dyed in the same dye bath under identi cal conditionsusing 0.25 percent by weight of the indicated dye and 0.1 percent TritonX100 an alkylaryl polyether-alcohol surfactant and the dyeing wascarried out at a pH 7.0 by raising the temperature over minutes to 95C.,and holding at 95 C. for minutes. The results of these dyeings are shownin table 2.

The dye strength is an observation of the color strength of the dyedfibers versus the standard nylon 6 control fiber, the evaluation beingcarried out under a MacBeth lamp. A change of 10 percent in fiber dyestrength is visually distinct to an ordinary observer and isapproximately equal to a change of 10 percent in the amount of dyestufiadded to the bath.

it can be observed that all of the azo dyes having an electron by theapproximation of 2.5 times that of the apparent electron affinity valuescited in this instant invention.

affinity greater than 3.0, when used in dyeing polyblcnds, exhibit adyeing strength equal to or superior to nylon 6 in competitive dyeing. i

This increase in dyeability over nylon 6 is unexpected when it wouldhave been predicted that nylon 6 containing polyester would have dyedwith significantly lower dye strength that the parent control nylon. Toillustrate this a polyester fiber dyed in a similar manner exhibitedvery light staining of between 5 and 10 percent dye strength of thenylon control. Specifically, color lOl X gave a dye strength of 5percent for polyester, for a nylon 6 a dye strength of percent, and for30 percent polyester content polyester/polyamide blend, a dye strengthof 180 percent. Dye color number 102X gave a dye strength of. 10 percentfor a polyester fiber (polyethylene tcrephthalate), 100 percent for thenylon 6 control and 170 percent for the polyester/polyamide blend. Thisdye has an electron affinity of 9.53. Dye color number 103x gave apolyester fiber dye strength of 15 percent, a nylon dye strength of 100percent and a polyester/polyamide blend fiber dye strength of percent.

More significant still, the polyblcnd yarns exhibited a con siderablyimproved light fastness as compared with the nylon control yarns whendyed under identical circumstances.

in carrying out this invention, the fibers may be dyed employingconventional techniques and commercial dyeing equipment. Low pressuremay be used as well as high-pressure, high-temperature equipment.

Conventional dye auxiliaries such as wetting agents, emulsi- I fyingagents, carriers, sequcstrants, swelling agents, developers, protectivecolloids, stabilizers, and the like may be I used. it is preferred toutilize nonionic or weak anionic surfactants such as alkyl arylpolyether alcohols. Condensates of ethylene oxides with long-chainalcohols and polyoxycthylene TABLE 2 Measuod Dye ye stren cl 1Dye colorColor Apparent strength fr m n PE-PA index electron vs. nylon FigureAsslgned Color N0. blends code 1 Formula or color lndex title nmnlt 101XBurnt (.1 1

orange. C 11 180 N -N N--- N()9 C 11 102K Brown Cl CH3 9.66 170 172()gN- -N=N N\ 1 2 1CEN U1 Scarlnf... 11230 CH3 9.08 165 (CH2)2CEN N OzN=N N\ (CH;) OH

103K Brownish C111 Cl 8. 48 160 15.!

red. I l

C2H4CEN Yellow 11310 8. 21 145 156 O,N N=N NH2 106K Orange '31 H 5. 97110 128 02N =N N\ CQHOII Blue 11420 Br /CH2CH-OH 5.3 130 120 1 011;O1N--N=N NH Orange 11100 Disperse Orange 3.88 105 104 N0 N=N N RednuDisperse Cl CH1 3.78 1. 101

Red 32, 011 11100.

O2N- N=N N CpHrOII Cl Red 11110 Dlsperse RedI 3.0 90 92 107);Brlghtscar- CH3 3- 85 1012 red. I /C2H1OH CQIIIOII Orange 11005 DisperseOrange 3 85 Red. 11150 Dlsperse Red 7 37 133 Table 2-Conlinuctl MeasuredDye ye strength Dye color Color Apparent strength from in PE-PA indexelectron vs. nylon Figure Assigned Color No. blends code l Formula orcolor index title umnity 6 I lX Yellow Dispcrsc l. 0 80 X0 Yellow N=N- vN=N -0 II 23.

104K Bluo-hlack Dispcrsc Cl 0.28 60 58 Black 3. I

inn N- N Nil:

Volumo 3, 2nd Edition 1956 Colour lnriox" joint publication, Soc. DyIcrsand Colourists and American Assoc. Textile Chemists and (Jo orists.

surfactants are especially useful. Catatonic surfactants can be employedif the azo dyestuff has not been previously dispersed by themanufacturer using anionic surfactants. If anionic surfactants have beenemployed by the the manufacturer of the disperse azo dye, agglomerationof the dye may occur if cationic surfactants are used during dyeing.

While carriers such as benzyl alcohol and the like can be employed, itis especially advantageous of this invention that they can easily beomitted while still obtaining deep shades and short dye cycles. Thedisperse dyes are applied in the form of a fine, typically colloidal,suspension of the dye in an aqueous medium. Such suspensions aregenerally prepared by grinding the dye in a colloid mill and the like inthe presence of a suspension of dispersing agent such as Naccatan Awhich is a sodium salt of a sulfonated naphthalene condensation product.

The dye concentration by weight of fabric would generally be in theorder of about 0.1 to 0.5 percent for light shades in apparel wear and0.5 to 2.0 percent for outer wear; for medium shades 0.5 to 1 percentfor apparel wear and l to 2 percent for medium to dark shades on outerwear. For heavy shades l to 2 percent for undergarments and 1% to 4percent for outer wear dark shades.

All percentages are expressed as percent by fabric weight of dyestuffemployed. The dyeing is typically carried out at elevated temperaturesof at least 70 C. and more preferably from 90 to 98 C.

The preferred operating temperatures may vary with particular dyes. Thedyeing times will vary depending upon the nature of the dye, the fabricconstruction, the dye concentration, the temperature, and the dyeapparatus employed. Typical dyeing times will be in the order of about0.5 to 9.0 hours.

The optimum temperature for the preparation of particular products willvary with the dye and with the blend employed. This can be detennined bytesting a series of dyes over a range of temperatures. In general, itmay be said that the maximum rate of dye absorption and improved dyeleveliness is obtained at the higher dye temperatures, specificallythose from 90 to 100 C.

In general, the novel dyeing process of this invention is particularlyinsensitive to change in pH in the range of 3 to pH. A pH of less than 3is generally avoided because at this low pH and at the temperaturesemployed in the dyeing process, chemical attack on the fiber may occur.in the dyeing of carpets it may be necessary to dye at as high a pH as10.0 in

order to avoid undue discoloration from the jute backing. It is anadvantage that the disperse dyes of this invention have excellentaffinity for the polyester/polyamide blend fibers whereas typical nylonfibers tend to become stripped at these higher pH levels.

We have now found unexpectedly that it is possible to produce animproved wide range of colors and to considerably expand the dye effectspossible in fabrics employing PE-PA blends and disperse dyes having ahigh apparent electron affinity for the polyblends. It is possible forinstance to use various polyestcr-polyamide blend fibers and to showtone-ontonc dye color efi'ects (a substantial shade difference).

A second azo group attached to a mono azo group has an electronattracting nilinity of 3.6.

Polyblend fibers having from 4 to 50 percent polyester concentration,can be used with or without a monoazo dye having a high electron dyeafi'mity to show substantial shade differences. If a nylon 6 fiberhaving greater than 40 amine equivalents is added to the fabric, anothershade difi'erence is possible. If nylon 6,6 is added which hasapproximately to amine equivalents, a further shade differential can beobtained. If for instance a nylon 6 is employed which contains less than30 milliequivalents per kilogram of tenninal amine groups a differentshade is also obtained. These differences are less apparent in thedisperse dyes. Thus, in the simplest 0 form, this invention can beapplied to fibers prepared from polyester/polyamide filaments containingdifferent proportions of polyester to obtain a plurality of shades fromonly one dye in one dye bath. By adding two dyes, one an acid dye andthe other a disperse dye of similar shades, the contrast in colors canbe accentuated, particularly the color difierence between the PE-PAblend fibers of this invention and nylons. Indeed with many of thedisperse dyes having particularly high affinity for the PE-PA blendfibers there is sufficient difference of color so that there is acomplete color change, nylon 6 being a light tan color with dye colornumber lOlX and the PE-PA blend fiber (30 percent polyester 70 percentnylon) being a deep burnt orange color. When color number I02X isemployed, the PE-PA blend fiber is a reddish brown color while nylon 6dyes a scarlet color. With color number l03X, 30/70 PE-PA melt blendfiber dyes a deep scarlet whereas nylon 6 dyes a light pink color.

Thus, by selecting a series of acid dyes or acid metallized dyes ofsimilar shades, these color differences can be emphasized or alternatelyleveled so that they are dyed identical within a single fabricstructure. In most cases it is desired to have substantial shadedifferences, therefore it is a special advantage of this invention thata wide variety of shade differences can be obtained using single ormultiple dyes within a dye bath. By adding other fibers such aspolyester and a fiber with at least percent polyacrylonitrile orpolyolefin fibers or by adding natural fibers such as cotton, wool,these shade differences can be further accentuated and novel patternfabrics can be produced using a woven structure and dyeing it 60 in asingle bath. Still another aspect of this invention resides in the factthat by taking advantage of the novel affinity of the PE-PA blendfibers, then adding dyes of different colors having different afiinitiesfor the PE-PA blend fibers, and adding a nylon fiber plus othersynthetics, a knitted or woven fabric can be produced and dyed in a dyebath with different colors whereby a wide range of colors can beproduced in the woven fabric in a single operation. Also, by selectionof various dyes, various dye concentrations, various pH levels, variouspolyester/polyamide fibers having various polyester contents, a widevariety of new and useful products can be produced.

Polyester/polyamide fibers dyed in accordance with this invention arecharacterized by very deep, brilliant shades, brightness and singularlyoutstanding light fastness with azo disperse dyes of high electronaffinity and have relatively good wash fastness and good resistance tocrocking. Because of these desirable attributes, fabrics of outstandingcolor and multicolor or tone-on-tone effects with a crisp, clear andbright appearance can be obtained. The finished goods constructed fromnylon yarn are useful for apparel fabrics as well as decorative fabricssuch as draperies, rugs, slip covers, upholstery, etc., because of itsremarkable afiinity for most dyes employed, and particularly, betweendifferent nylons in which case it is quite difiicult to obtainsubstantially different colors. We have however found that the PE-PAblends of this invention yield very bright colors clearly defined fromthe polyamides employed. This is often impossible with nylon fabricsincorporating other fibers, of natural or synthetic fibers, since nylonheavily cross dyes with many classes of dyes used. We have found that byweaving or knitting various yarns and using dyeing processes asdisclosed in this invention that fabrics can be produced which havemulticolors or tone-ontone shades that follow the characteristic of theparticular fiber introduced. By using, for instance, a box weave patternand selecting dye combinations, attractive patterns can be incorporatedin the fabric so that rugs, upholstery fabric, knitted goods, and thelike can be dyed in mass in a series of colors and/or in tone-on-toneeffects hitherto impossible to achieve with nylon along.

We have found in the process of this invention that it is possible tosubstantially modify the PEPA blend fiber and that the stylist and thedyer can now produce dyed fabrics with greater differences than has beenpossible in the past. They can extend the range of dyes which can beemployed for the novel dye effects and because of the remarkableaffinity of the PE-PA blend fibers of this invention, the resultant dyedproducts have unique and outstanding dye fastness properties as comparedwith nylon alone. Among the methods which may be employed to modify thefibers of this invention and the process parameters which may be used tomodify the color effect of the process of this invention are thefollowing:

1. Selection of different PE-PA blend fibers having different polyesterconcentrations.

2. Selection of PE1PA blend fibers wherein different shear effects havebeen carried out to produce a greater number of polyester fibrils for agiven filamentary cross section, with the greater dye strength beingobtained with fibers having greater number of polyester fibrils per unitcross section for a given polyester concentration.

. Selection of critical concentrations of dye to emphasize the shadedifferences between nylons.

4. Selection of different dye types, that is a deep dyeing, highelectron affinity disperse azo dye for the polyester/polyamide blendfiber and an acid dye of similar shades for the polyamide fiber. This,along with critical selection of concentration of the dyes employed,results in unusual color effects.

. Because of the relative insensitivity of the PE-PA blend fibers tochanging pH with acid dyes, and since the dye affinity of nylons can bematerially changed for the acid dyes with change in pH, a change in thedye contrast between the nylon and the polyester/polyamide blend fiberemployed can be obtained.

6. By use of an electrolyte such as NaCl and lKCll to decrease thesolubility of acid azo dyes having typically in the absence of the acidgroup a high electron affinity, the acid dyes or acid metallized azodyes tend to act as disperse dyes and take on the character of theirparent disperse dye types. In this manner the PE-PA blend fibers tend toselectively increase their dye strength at a greater rate than doesnylon fibers given a similar treatment in the same dye bath. A

7. By use of colorless mono, di, or trisulfonic acids to selectivelyblock the amine end groups of the nylon 6 or 6,6 components therebydecreasing their dye absorption in the presence of acid dyes withoutmaterially affecting the dye absorption in the PE-PA blend fibers.

8. By selection of nylon having different terminal amine end groups, thepercentage absorption of acid dyes and acid metallized dyes can bematerially altered.

In table 3 which follows, the effects of spinneret shear upon therelative ability of the PE-PA blend fibers to absorb high electronafi'mity azo dyestuffs is illustrated. in this case a 30 percentpolyester polyamide blend fiber is employed and the change in dyestrength is noted as compared to a controlled nylon polycaproamide fiberhaving a dye strength of percent. A 0.25 percent dye by weight of fiberwas employed and the fibers were dyed in a manner described for table 2.

The dye type employed was 102)(. A similar effect of in creasing dyestrength is noted using lower polyester concentrations, say 10 percent,or higher polyester concentrations, say 50 percent, with the effect ofincreasing number of polyester numbers per given filamentary crosssection being emphasized with the increased polyester concentration.Thus the effects of increasing the shear within the spinneret is moremarked at the higher polyester concentrations than at the lowerpolyester concentrations.

Definitions and Tests: in the course of the previous description andfollowing examples, the following tests and definitions are used todefine more fully the process and technology employed.

DYE STRENGTH The dye strength of the fibers is rated under a MaclBethlamp by an experienced colorist. A control polycaproamide having greaterthan 40 milliequivalents of amine end groups per kilogram of polymer isnormally employed and is rated at 100 percent when dyed competitivelywith the fiber being compared with it. Thus a dye strength of percentfor 1 percent by weight of fabric for standard dyeing is equal to thatobtained when dyed with 1.1 percent dye per weight of fabric. Similarlya 05 percent dyeing per weight of fabric rated as a dye strength of 1 10percent is equal to a dyeing of the standard with 0.55 percent dye perweight of fabric.

REDUCED VlSCOSllTY The reduced viscosity of polyesters and polyamides asem ployed in this specification was determined by viscosity measurementscarried out on a sample of polymer dissolved in purifiedorthochlorphenol containing 0.1 percent water, and maintained at atemperature of 25 C. and a polymer concen tration of 0.5 percent duringthe determination and is ex pressed as deciliters per gram.

Disperse dye used color indentity number and formula:

0.25 percent by fabric weight dyed at pH of 7.0. Apparent Electronaffinity 9.56.

The apparent mixing shear within the extruder is expressed in reciprocalseconds and it equals 11 (diameter of screw in inches)(revolutionspersecond) thread h eight in metering sections The apparentshear in reciprocal seconds: This is calculated from the equation is.)1R3 7 EXAMPLES 1 THROUGH 33 The polyester/polyamide blend fibers wereprepared by blending together particles of polyethylene terephthalatehaving a reduced viscosity of at least 0.3 deciliters per gram and whereq volumetric flow per second or blend throughput in s .wlycaproamlde afj f t fn l 8t i' t pounds per second divided the density in pound percubic eclol ers per gram an ex m e a a e pe ure foot. R equals theradius of the spinneret hole in feet cubed. and apparent sheaf of atleast I reciprocal seconds The apparent shear at the spinneret is basedon one spinneret wnhmd i g a m i g g zs hg 5:52:21 hole. Thus shearvalues obtained are divided by the number of Secon E amen were pr y gten polymer in blend at an apparent shear within the splnneret spinneretholes used for the total flow employed. The followof at least greaterthan 2,100 reciprocal seconds and in most mg are the dens1t1es of moltenmaterials for this calculation:

of these examples greater than 6,000 reciprocal seconds. TA E 4 The spunfilaments were then passed through a quench zone Density in Grams l5 andtaken up as yarn at a birefringence of less than 0.0055. lt PercentPoly- Per Millil was then drawn at a speed of 840 feet per minute at thenoted P l T gr: 331? draw ratio. Drawn yarns were conditioned for 24hours at 25 ycapmam' c mp a m C. and at a relative humidity of 65percent before the physical properties which are cited herein weredetermined. '33: i :3; Dyeing is carried out using the noted dyeconcentrations 100% 1.21 (expressed as percent dye based on the totalfiber weight).

20% The percent dye in the dye bath is nominally 1.0 percent by 70% 30%weight of the fiber tested. To achieve the improvement in dyeao z 40%1,09

50% 50% MI mg over nylon, the PE-PA blends must have, in the drawnstate, at least 5,000 polyester microfibrils per 1,000 square micronfilamentary cross section. The polyester fibers should PREFERREDEMBODIMENTS not have a drawn diameter which exceeds 0.3 microns and theThe examples given below illustrate the practice of certain Polyesterfibnls Should a a length wh'ch preferably at specific embodiments of theinvention. It will be understood 3() least 300 Polyester d'ameter'however that the invention is not limited to the specific emeXamPleS Q,h polyblend melt blend fiber was bodiments herein disclosed, butincludes all modifications and pr p re by B mlXlng I0, 30, and 40percent polyester variations thereof which are apparent to those kill di h (polyethylene terephthalate in an extruder at an apparent n shear of1 l5 reciprocal seconds at a temperature of 265 0,

TABLE 5 Nylon 10% 6, polyester. polyester, polyester, Nylon 6,6 Nylon 6,termi- 70 0 0 0 Polymer properties control control noted polyamidepolyamide polyamide E nd groups as carboxyl 1 106 60 66 75 75 75 Endgroups as amines 27 9 6 6 6 Polyester phase:

End groups as carboxyl 55 55 End groups as hydroxyl 56 56 56 PolyesterOCPR viscosity 0. 8 0. 8 O. 8 Nylon OCPR viscosity .8!) 1.11 1. 21 1.0551.055 1.055 Spinning conditions,

temperature spun, C. 1 275 265 270 270 268 "i0 Extruder mixing shear,reciprocal seconds 68 72 116 110 Mixing shear within spinnerette,reciprocal secs 2, 530 2, 530 2, 530 6, 350 6, 120 6, 500 Temperature ofdrawing,

(1 185 185 186 185 185 18 l)rnwratio 4.2 4.1 4.2 4.4 4.3 5.2 Drawndiameter PE fibril n 1 1 1 138 .193 .04 Drawn PE fibril length/ (iia 11, 070 1, 000 5, Number of PE fihril/ 1.000 1 20, 000 14, 100 55, 000Ultimate tensile strength 4. 4 4. 8 4. 3 7. 2 7.0 7. 1 Ultimateelongation 28 31 32 26 23 17 Stiffness index. UTS/UE 16 .15 .134 .28.305 .417 Initial tensile modulus,

god 22 25 34 58 66 52 Hot-wet strength. g.p.d 2. 8 3.1 4. 9 4. 9 Hot-wettensile modulus,

g.p.d 14 16 37 4o 43 Shrunken tensile modulus.

g.p.d 11 10 20 25 15 Percent tensile recovery at 1% elongation s0 81 8588 83 Percent work recovery at 1% elongation 1 51 50 70 73 60 Percentstress decay at 1% elongation 27 26 17 16 3 Yield stress in water at21C. .d .30 .30 1.0 1. 02 .60 Yield point in g./d. in air,

at 70 F.. 65% R.H .69 .68 1.20 1.22 1.0 Yarn denier 120 120 120 120 120120 Number filaments 20 20 20 20 20 20 Milliequivalents per kilogram ofpolymer. The data are based on the analysis of the polymer before meltblending and spinning.

Typical values for nylon 6 control and the terminated nylon 6 fiber are,in general, equivalent.

IOIOIQ 0110 the polymer being dried to a moisture content below 0.05percent prior to blending. The molten polymer upon exiting from theextruder passes through a pump, thence through suitable filtrationmedium involving a sand pack wherein a suitable velocity was maintainedabove 40 reciprocal seconds) to avoid agglomeration and growth of thepolyester dispersed spheres.

Upon exiting from a sand pack, the polymer passed through a 20-holespinneret at an apparent shear within the spinneret of 6,300 reciprocalseconds. The polymer feed rate was 3.8 pounds per hour or 0.l9 poundsper hour per spinneret hole. The yarn was then passed through a quenchzone and taken up in a conventional manner.

the fibers conform to that as illustrated. in table 5. The dyedescriptions are as outlined in table 2. The relative percent dyeabsorbed is as described above.

The dye bath, a pH was adjusted by addition of acetic acid for pH below4% and ammonium sulfate for attainment of a pH of 4.5. For attainment ofpH above 7 a dilute solution of sodium hydroxide was added to attainthe: desired pH.

In tables 6 and 7 in subsequent examples the following definitions applyto identify the class of dyes employed.

Class l, acid soluble dyes, anthraquinone-type.

Class 2, acid dyes generally azo-type.

Class 3, direct dye, soluble-type.

Class 4, disperse dye, generally a disperse anthraquinonctype. Yarn wassubsequently drawn at the indicated draw ratios 1 5 and test portion wascrimped using a stuffer box crimper to zi z zi afield d f ofgyc toproduce crimped yarns having 13.0 crimps per inch. Non- 0 me genera yneuyra yes 0 m PH and the metal atom is generally either chrome orcobalt. crimped yarns were wound up on packages to produce 120 de- C]ass 6, Disperse dye, azo-type insoluble having a low elecnier, 2Ofilament yarn, and was subsequently twisted to have one third tum erinch 70 tron affinity of below 3.0.

Class 7, Soluble metallized dye, one atom of metal to l in preparationof the dye dispersion, thedyes were pasted molecule f soluble acid dye.meta] is generally with water and 0.5 percent, based on the weight ofthe fiber of chrome and the dyeings are generally on the acid Side at analkyl aryl polyester alcohol surfactant. Dyeing was carried 40 to 61) PMout at a temperature of 95 C. for 1 hour at a pH as indicated Class 8, Abasic dye. utllllmg y flfldloimly dyeing p y i fibers of Various Class9, A dispersed dye, azo-type. water insoluble, less than Percentage P llcuncemraflon with the Polyamldes 0.l gram per 100 cc. of water and whichhas an apparent under the conditions as outlined in table 6. Theproperties of ele tro aff nity of greater than 3,0.

TABLE 6 10% 30% Electron Percent Nylon 6, Nylon 6, polyester polyesterpolyester afiinity Test variable dye Nylon 0,6 control terminated blendblend bl *5 of dye ()OP R fiber viscosity 8 l1 21 1. 04 .98 .05 Meq.amine end Group 27 9 Mcq. carboxyl end groups i 0 45 66 Dye Dye,identity Pei-cent dye strength vs. nylon 6 control class employedExample p11 1 7. 0 25 80 100 90 130 180 185 9. 9 2 10. 0 26 90 116 170175 J. 9 i 7. 0 25 78 100 95 125 160 170 8. 4 4 10, 0 25 70 85 115 155165 8. 4 Disperse orange 5.... 5 7. 0 25 85 100 00 100 106 110 3. 8 o 610.0 .25 70 S0 05 3.88 11420 disperse blue. 7 7. 0 25 J0 100 90 121) 1305. 3 do 8 10. 0 .25 80 86 80 100 5, 3 DlSDQlSQ orange 3.... 1i 7. 0 2580 100 85 90 35 70 g 45 o 10 10.0 .25 80 86 75 80 80 76 2.45 107X brightscarlct 11 7. 0 25 86 100 90 90 85 90 3. 0 d 12 10.0 .25 75 90 80 80 81)85 3,0 do 13 7. 0 1.0 90 100 80 70 c1) 50 2 Milliequivalents of amineend groups per kilogram of fiber. Milliequivalcnts oi carboxyl groupsper kilogram oi fiber. See Table 4A [or yarn and polymer properties. SeeTable 2 ior (lye description 01 azo disperse dyc with high electronaffinity.

TABLE 7 Ex. Dye Dye Percent Electron Foo t- Nylon (1, Nylon 0, 10% 30%40% No. description class dye p11 affinity notes Nylon 6,6 controlterminated polyester polyester polyester 14 Direct 131111176. 3 5 7. (l15... 13asicBluo22 8 .25 7.0 Acid Blue 145... 1 .5 7.0 17 Acid Brown10.. 5 0.5 7.0 18 0...... 5 0.5 3.0 1S) .......do...,....... 5 0.5 10.020 Acid Blue 40.... 1 1.0 7.0 21... Acid Red 207. 7 25 4. 5 l2 Acid Blue10,v l .25 7.0 23 Acid Blue 40 l i 25 7. 0

plus 20 grains N aClz. 24".. Acid Blue 40 1 1. 0 7. 0 r I a i 1.0 10. 07 do 1 .25 11.0 I Acid Black 63.. 5 1.0 7. 0 95 d0 5 26 7. 0 1

2 .5 7.0 Orange red Tan 40 70. ..do. 2 2.0 7.0 Red 60...... Scarlet70... Pink 60... Pink 40. Acid Orange 2 .5 7. 0 Yellowish Light orangePink 20. Pink 15.

orange 80. 50. 3 Acid Yellow 38.. 2 1 0 6-0 70 90 70 60. 33 Acid Red114.... '2 5 7-0 70 80 30. 34"... Acid Green 25. 1 1. 7- 0 60 80 50 40.

* Control for Examples 18, 19. Control for Examples 22, 23, 24, 25. Plus6 grains per liter dye bath colorless alkyl naphthalene moiiosnlionate.Add iimiiioiiio and drive it oil iii. a boil to favor color depositionon rapid dyeing products. Control for run 28.

TABLE 8 Light iastness of azo disperse dyes applied to 30% polyester,70% nylon Polyblend (all dyeings nt 1%) Light fastness, 30/70 PolyblendLight Dyo fastness, Dyestufl, strength W.O. nylon 6, sec Electron vs.(Ll. hours Rating W.O. hours Table 2 affinity nylon Dye name number 20 410 101K 9. 9 180 Burnt Oran e 30 6 2.0 80 Disperse Ye low 11855 100 6-780 105K 2. 0 80 Disperse Yellow 23 40 40 103K 8. 48 160 ScarletNorE.-While the above light iastness ratings show little correlationwith the apparent electron aifinity of the (lyestufl employed, it is asignificant advantage that all fibers tested show a light fastness atleast equal to or superior to the nylon control employed. (All tests inTable 7 were based on 1% dye based on weight of fabric.)

TABLE 0 Component A Component B Example Example Component 1 Nylon 6 Ex.N0 Percent Dye No Percent electron Nylon Nylon 6 termi- 10% poly- 30'};poly- 400;. poly- No Table I dye class Table 6 dye aflrnity 6,6 controlnoted ester ester ester Polyester 39. 14 .5 3 1 .25 0. 0 Light BlueNavy... Dark Brown Brown" Light ivory. navy. orange. 40. 15 .25 8 3 .268. 5 Gi'eenish Yellow Yellow Greenlsh Green"... Green... Light yellowyellow yellow. 41 .21 1 7 25 5. 3 Violet Reddish- Vi0let. Reddish BlueBluru Blue blue. violet stain. 42. 32 .5 2 7 .25 5. 3 Greenish Yell0wGreenish Olive Green Green Do.

yellow. yellow. green.

1 See column line The 120 denier, 20 filament, AZ twist yarn was knittedon a circular knittcr into 2-inch wide bands so that each fiber whendyed was a, distinct as a 2-inch band. The knitted sleeves were scouredwith 0.2 percent Naccanol SL, detergent and 0.2 percent sodium carbonateand were dyed in the processes indicatcd above.

Each 2-inch band contained one fiber; a polyhexamethylenc adipamide, anylon 6,6 fiber; a polycaproamide fiber having greater than 40milliequivalents of terminal amines per kilogram of polymer; a secondnylon 6 fiber having less than 20 millicquivalcnts per kilogram ofpolymer of terminal amines; a 10 percent polyester, 90 percent polyamideblend; a percent polyester, 70 percent polyamide blend, and a 40 percentpolyester, 60 percent polyamide blend. In table 6 below, the effects ofpH and other process factors upon dye strength and dye shade can beseen.

Examples 1-13, as shown in table 6, illustrate the very largedifferences in a single color tonc-on-tonc depth obtained byintroduction of a combination of nylon and polyblcnd fibers andillustrates the significant differences in shade and color obtainable ina one-dye bath operation. Most significantly, the increase in dyestrength of the polyblends is altered substantially with increase inpolyester content and even to far greater extent by the effect of highelectron affinity dyes. The dye strength is proportional to the apparentelectron affinity of the dye, that is, with a higher electron affinityazo disperse dye there is a significant increase in the amount of dyeabsorbed with an increase in the polyester content. This can be furtherinfluenced to a limited extent by changes in pH.

Table 7 illustrates the counter effect of a decrease in dye absorptionwith an increase in polyester content for direct, acid and prcmetallizeddyes. Therein is illustrated a variety of ways of achieving multicoloredfibers and/or tone-on-tonc effects by means of selection of the dyes,where the lower dye absorption of polyblends vs. the nylons is employed.Thus, by careful selection of high electron affinity dyes and lowabsorption acid or premetallized dyes on the polyblend, very distinctand clear-cut separation of colors can be obtained between nylon and thepolyblend fibers in a textile structure. This property is especiallyvaluable producing multicolored fabrics by dyeing in a single bath withthe various dye types.

Since the PEPA polyblend fibers dye deeply, with azo disperse dyes ofhigh electron affinity at pHs up to as high as l0, this pH effect can beused as a means to further emphasize the shade and color differencesbetween nylon and polyblends.

Examples 29, 30, 31 and 2] are all illustrations of the very large colordifferences which can be obtained for tone-ontone dyeings.

Table 9, examples 39-42, illustrates use of an azo dyestuff with highelectron affinity with a second dyestuff such as acid premetallizeddyestuff, as a component A, and a disperse dye, as component B. It canbe observed in table 9 that a complete change or separation of colors isobtained. The foregoing example illustrates that this invention providesfor a fiber and a method of dyeing that fiber to obtain separate andmulticolor effects between nylons and polyblends and thereby achievemulticolored patterns in fabrics. Because of the similarity of the handof the polyblends and nylons, the fabric structures made from mixturesof these fibers and dyed in a common bath have along with a good colorseparation and change in colors similarity of hand and stress-straincharacteristics which are of substantial utility.

What is claimed is:

l. A dyed fiber comprising a polyester/polyamide blend fiber dyed withan azo disperse dye having a solubility of less than 0.l gram in lOO cc.of water and which has an apparent electron affinity of greater than 3electron volts, said fiber comprising a uniform dispersion of 4 to 50parts by weight of a fiber-forming polyester selected from the groupconsisting of polyethylene terephthalate and polyethylene isophthalatein a continuous body of 50 to 96 parts by weight of a fiber-formingpolyamide selected from the group consisting of polyhexamethyleneadipamide and polycaproamide per 100 parts by weight of total polyamidcand polyester.

2. The dyed fiber of claim 1 wherein the polyester has a reducedviscosity of about 0.3 to 1.1 deciliters per gram, the polyamide has areduced viscosity of 0.6 to 1.3 deciliters per gram, and the polyesteris dispersed in the polyamide in the form of discrete microfibers whichoccur at an average of at least 5,000 polyester microfibrils per 1,000square microns in a drawn filament cross section.

3. The dyed fiber of claim 2 in which the azo disperse dye contains 2 to4 electron attracting substituents selected from the group consisting ofC N,(CH ),,C N,NO ,X, and (CH,),,X, where X is a halogen and n is aninteger from 1 to 5, said electron attracting substituents beingattached to the aromatic ring structure of the azo disperse dye.

4. The dyed fiber of claim 3 in which there is present on the samearomatic ring structure of the azo disperse dye an electron repellingsubstituent; said electron repelling substituent being selected from thegroup consisting of N(CH NH ,-OH,OCOCH ,OCH and-CH said electronattracting substituents having an apparent electron charge of at least0.5 electron volts greater than the electron repelling sub- 7. The dyedfiber of claim 3 in which the polyester is stituents. polyethyleneterephthalate.

5. The dyed fiber of claim 2 in which the apparent electron 8. The dyedfiber of claim 3 being comprised of 10 to 40 affinity of the dye is 4.0to I electron volts. parts by weight polyester and 90 to 60 parts byweight polya- 6. The dyed fiber of claim 3 in which the polyamide ismide.

polycaproamide. =1: t II:

UNITED STATES PATENT OFFICE CETIFICATE OF CORRECTION Patent Nos-3,635,653 Dated January "IQ. 'IQTI Inventor(s) V Eu Snider t a1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

ABSTRACT: Line 9, "is" should be --,in-..

Column 2, line 59, "polyester" shouldbe -polye'sters. Column 4, line 11,"along" should be -alone-,.. Column 4, line 37, "group" should begroups,.

7 Column 4, line 60, after "charge" insert -relat ionsIhips--.

Column 4, line 68, "designated" should be -designate-.

Column 7, line 47, "groups" should be --group Column 8, line 48, "that"should'be -than. Column 13, line 22, "along" should be -alone--. Column18,

Table 6, under the heading, "Nylon 6,6" and in Dye Identity,

1 "Disperse Orange 3", "80" should be 90-. Table 7, .Under the Heading,"30% Polyester" in "Compound 33",

" 70' should be -40-..

The inventors: [72]"Orville En Snider" should be --Orvill E, SniderSigned and sealed this hth day of July 1972,

(SEAL) Attest:

EDWARD MELETCHER JR, ROBERT GOTTSCHALK Attesting Officer- Commissionerof Patents

2. The dyed fiber of claim 1 wherein the polyester has a reducedviscosity of about 0.3 to 1.1 deciliters per gram, the polyamide has areduced viscosity of 0.6 to 1.3 deciliters per gram, and the polyesteris dispersed in the polyamide in the form of discrete microfibers whichoccur at an average of at least 5,000 polyester microfibrils per 1,000square microns in a drawn filament cross section.
 3. The dyed fiber ofclaim 2 in which the azo disperse dye contains 2 to 4 electronattracting substituents selected from the group consisting of C N,-(CH2)nC N,- NO2,-X, and - (CH2)nX, where X is a halogen and n is aninteger from 1 to 5, said electron attracting substituents beingattached to the aromatic ring structure of the azo disperse dye.
 4. Thedyed fiber of claim 3 in which there is present on the same aromaticring structure of the azo disperse dye an electron repellingsubstituent; said electron repelling substituent being selected from thegroup consisting of - N(CH3)2,- NH2,- OH,-OCOCH3,- OCH3, and- CH3; saidelectron attracting substituents having an apparent electron charge ofat least 0.5 electron volts greater than the electron repellingsubstituents.
 5. The dyed fiber of claim 2 in which the apparentelectron affinity of the dye is 4.0 to 10.0 electron volts.
 6. The dyedfiber of claim 3 in which the polyamide is polycaproamide.
 7. The dyedfiber of claim 3 in which the polyester is polyethylene terephthalate.8. The dyed fiber of claim 3 being comprised of 10 to 40 parts by weightpolyester and 90 to 60 parts by weight polyamide.